.TH "RTC_GEOMETRY_TYPE_TRIANGLE" "3" "" "" "Embree Ray Tracing Kernels 3"
.SS NAME
.IP
.nf
\f[C]
RTC_GEOMETRY_TYPE_TRIANGLE\ \-\ triangle\ geometry\ type
\f[]
.fi
.SS SYNOPSIS
.IP
.nf
\f[C]
#include\ <embree3/rtcore.h>

RTCGeometry\ geometry\ =
\ \ rtcNewGeometry(device,\ RTC_GEOMETRY_TYPE_TRIANGLE);
\f[]
.fi
.SS DESCRIPTION
.PP
Triangle meshes are created by passing
\f[C]RTC_GEOMETRY_TYPE_TRIANGLE\f[] to the \f[C]rtcNewGeometry\f[]
function call.
The triangle indices can be specified by setting an index buffer
(\f[C]RTC_BUFFER_TYPE_INDEX\f[] type) and the triangle vertices by
setting a vertex buffer (\f[C]RTC_BUFFER_TYPE_VERTEX\f[] type).
See \f[C]rtcSetGeometryBuffer\f[] and
\f[C]rtcSetSharedGeometryBuffer\f[] for more details on how to set
buffers.
The index buffer contains an array of three 32\-bit indices per triangle
(\f[C]RTC_FORMAT_UINT\f[] format) and the number of primitives is
inferred from the size of that buffer.
The vertex buffer contains an array of single precision \f[C]x\f[],
\f[C]y\f[], \f[C]z\f[] floating point coordinates
(\f[C]RTC_FORMAT_FLOAT3\f[] format), and the number of vertices are
inferred from the size of that buffer.
The vertex buffer can be at most 16 GB large.
.PP
The parametrization of a triangle uses the first vertex \f[C]p0\f[] as
base point, the vector \f[C]p1\ \-\ p0\f[] as u\-direction and the
vector \f[C]p2\ \-\ p0\f[] as v\-direction.
Thus vertex attributes \f[C]t0,t1,t2\f[] can be linearly interpolated
over the triangle the following way:
.IP
.nf
\f[C]
t_uv\ =\ (1\-u\-v)*t0\ +\ u*t1\ +\ v*t2
\ \ \ \ \ =\ t0\ +\ u*(t1\-t0)\ +\ v*(t2\-t0)
\f[]
.fi
.PP
A triangle whose vertices are laid out counter\-clockwise has its
geometry normal pointing upwards outside the front face, like
illustrated in the following picture:
.IP
.nf
\f[C]
\f[]
.fi
.PP
For multi\-segment motion blur, the number of time steps must be first
specified using the \f[C]rtcSetGeometryTimeStepCount\f[] call.
Then a vertex buffer for each time step can be set using different
buffer slots, and all these buffers have to have the same stride and
size.
.PP
Also see tutorial [Triangle Geometry] for an example of how to create
triangle meshes.
.SS EXIT STATUS
.PP
On failure \f[C]NULL\f[] is returned and an error code is set that be
get queried using \f[C]rtcDeviceGetError\f[].
.SS SEE ALSO
.PP
[rtcNewGeometry]
